/**
 * Copyright (C) 2002-2015   The FreeCol Team
 * <p>
 * This file is part of FreeCol.
 * <p>
 * FreeCol is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 * <p>
 * FreeCol is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * <p>
 * You should have received a copy of the GNU General Public License
 * along with FreeCol.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.sf.freecol.common.io;

import java.io.File;
import java.io.FileFilter;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

import javax.xml.stream.XMLStreamException;

import net.sf.freecol.common.ObjectWithId;
import net.sf.freecol.common.model.Specification;


/**
 * A wrapped for a file containing a FreeCol modification (mod).
 */
public class FreeColModFile extends FreeColDataFile implements ObjectWithId
{

    protected static final String SPECIFICATION_FILE = "specification.xml";
    protected static final String MOD_DESCRIPTOR_FILE = "mod.xml";

    /** A file filter to select mods. */
    private static final FileFilter fileFilter
            = makeFileFilter( MOD_DESCRIPTOR_FILE, "fmd", ZIP_FILE_EXTENSION );

    /** The identifier for this mod. */
    private String id;

    /** The identifier for the parent of this mod, if any. */
    private String parent;


    /**
     * Make a FreeColModFile from a File.
     *
     * @param file The <code>File</code> containing a FreeCol mod.
     * @exception IOException if thrown while opening the file.
     */
    public FreeColModFile( final File file ) throws IOException
    {
        super( file );

        readModDescriptor( );
    }


    /**
     * Gets the input stream to the specification.
     *
     * @return An <code>InputStream</code> to the file
     *     "specification.xml" within this data file, or null if none present.
     * @exception IOException if thrown while opening the input stream.
     */
    public InputStream getSpecificationInputStream( ) throws IOException
    {
        try
        {
            return getInputStream( SPECIFICATION_FILE );
        }
        catch ( FileNotFoundException fnfe )
        {
            ; // Normal for graphic-only mods.
        }
        return null;
    }

    /**
     * Gets the Specification.
     *
     * @return The <code>Specification</code>, or null if none present.
     * @exception IOException if an error occurs reading the specification.
     */
    public Specification getSpecification( ) throws IOException
    {
        try ( InputStream si = getSpecificationInputStream( ) )
        {
            return ( si == null ) ? null : new Specification( si );
        }
    }

    /**
     * Gets the input stream to the mod meta file.
     *
     * @return An <code>InputStream</code> to the file "mod.xml"
     *     within this data file.
     * @exception IOException if thrown while opening the input stream.
     */
    private InputStream getModDescriptorInputStream( ) throws IOException
    {
        return getInputStream( MOD_DESCRIPTOR_FILE );
    }

    /**
     * Reads a file object representing this mod.
     *
     * @exception IOException if thrown while reading the "mod.xml" file.
     */
    protected void readModDescriptor( ) throws IOException
    {
        try (
                FreeColXMLReader xr
                        = new FreeColXMLReader( getModDescriptorInputStream( ) );
        )
        {
            xr.nextTag( );
            id = xr.readId( );
            parent = xr.getAttribute( "parent", ( String ) null );
        }
        catch ( XMLStreamException xse )
        {
            throw new IOException( xse );
        }
    }

    /**
     * Gets the object identifier of this mod.
     *
     * @return The object identifier of the mod.
     */
    @Override
    public String getId( )
    {
        return id;
    }

    /**
     * Gets the parent of the mod.
     *
     * @return The mod parent name.
     */
    public String getParent( )
    {
        return parent;
    }

    /**
     * Get the file filter to select mod files.
     *
     * @return The mod file filter.
     */
    public static FileFilter getFileFilter( )
    {
        return fileFilter;
    }
}
